The first record of signal crayfish, Pacifastacus leniusculus (Dana, 1852) and its projected expansion in Serbia under global climate change

Mladen Antun Horvatovic, Milica Ranković, Dubravka Milić, Branko Miljanović, Aleksandar Bajić


The signal crayfish invasion through the Drava River towards the Danube and Serbia poses a significant threat to the indigenous astacofauna of the region. Our research aimed to determine whether it had already reached the Danube and predict its future spread in Serbia. We recorded one specimen for the first time in the Serbian Danube at 1280 rkm. With the rate of 152 km in two years, the invasion was seemingly extremely fast. It seems likely that signal crayfish reached the Danube as early as 2014-2015 due to accelerated expansion through the Drava. Using Species Distribution Modeling, we predicted its potential distribution in Serbia until 2050 and 2070, based on climate change models. Scenarios show its expansion along the Danube and its tributaries, almost across Serbia, with the most substantial impact in the northern and central regions and slightly weaker in the south. In addition to already weakened indigenous Pontastacus leptodactylus and Astacus astacus, signal crayfish could reach habitats of so far isolated Austropotamobius torrentium. New waves of crayfish plague, combined with competition, could have a devastating impact on Serbian astacofauna and astacofauna of Eastern Europe, the region with arguably the richest crayfish diversity in Europe.

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